"Sotheby’s is an art market machine," Jeffrey Deitch told me many years ago. You can see it in action any time, just by visiting the firm’s elegant headquarters building on York Avenue and 72nd Street. It’s an insider’s secret -- while the hipsters hit Chelsea and tourists trip to the museums, the money crowd visits the auction houses to check out the coming week’s wares. No problem, the driver will wait with the car at the curb.